Burner control system having opposing thermoelectric generators



J. A. WOLFF June 23; A1959 BURNER CONTROL SYSTEM HAVING OPPOSING THERMOELECTRIC GENERATORSy Original Filed July 25, 1950 ATTORNEY United States :Patent BURNER CONTROL SYSTEM HAVING OPPOSING THERMOELECTRIC GENERATORS John A. Wollt, Milwaukee, Wis., assignor to Baso Inc., Milwaukee, Wis., a 'corporation of Wisconsin Original application July 25, 1950, Serial No. 175,776.

Divided and this application February 19, 1954, Serial No. 412,305

2 Claims. (Cl. 158-131) This invention relates, in general, to therrnoelectrically controlled fuel burning systems, and has particular relation to an improved burner control system having a thermoelectric device comprising a plurality (i.e., two or more) of therrnocouples or other thermoelectric generators (such as thermopiles), or combinations thereof, connected in circuit with each other in opposing relation.

The present invention is a division of my copending application, Serial No. 175,776, filed July 25, 1950.

One of the main objects of the present invention is to provide a burner control system having at least one burner, and a safety shut-off device controlling the ow of fuel to the burner or burners and operated by the electric current generated by a therrnoelectric device of the character described.

Another object of the invention is to provide a fuel control system having a plurality of thermoelectric generators connected in circuit opposing relation so that the opposing thermoelectric generator may be arranged to be heated to deenergize, for example, a magnet coil energized by the other thermoelectric generator; or in the manifold or mixing chamber of a gas burner as a safety hash-back control; or as a means for a timed control; or as a high temperature safety shut-oil; or so that the plurality of thermoelectric generators will interact in timed relation to each other.

While I shall disclose certain illustrative applications of -the present invention, it is to be understood that the invention is not limited to such applications but may be employed for other purposes as suitable or desired.

Other objects and advantages and numerous adaptations of the invention will be apparent from the following detailed description and the accompanying drawings.

In the drawings:

Figure 1 is a longitudinal sectional view taken axially through a thermoelectric device 'as embodied in the present invention;

Figure 2 is a transverse sectional view taken on the line 2-2 of Figure 1;

Figure 3 is a wiring diagram showing the thermoelectric circuit for the device shown in Figure l; and

Figure 4 is a more or less diagrammatic view showing one embodiment of the present invention in which the thermoelectric device is arranged for safety pilot and safety flash-back control.

Referring to the drawing, the thermoelectric device embodying the invention of the copending application, Serial No. 175,77 6, now Patent No, 2,691,056, as therein illustrated comprises a thermoelectric generator shown in the form of a coaxial thermocouple 1 with coaxial lead conductors therefor, in general, of the type disclosed and claimed in Oscar J. Leins Patent No. 2,126,564, patented August 9, 1938.

The thermocouple 1 comprises an outer tubular thermocouple element 2 enclosing an inner thermocouple element 3. The elements 2 and 3 may be formed of any suitable or preferred dissimilar thermoelectric materials.

Yree

The element 2 may, for example, be formed of stainless steel, copel, constantan, Chromel, or any other metal in the thermoelectric series well known in the art, and the member 3 may be formed of the opposite or dissimilar metal separated in the thermoelectric seriesV from the metal from which the element 2 is fonned. While dissimilar metals in the thermoelectric series are referred to, it is to be understood that the elements 2 and 3y may be formed from dissimilar thermoelectric alloys or from any other dissimilar thermoelectric materials whichQwhen joined together and heated at the hot junction, willv produce a thermoelectric current.

`It is to be further understood that the thermoelectric generator 1 may be in the form of a thermopile which, as well known in the art, comprises a plurality of thermocouples connected in series.

In the particular embodiment of the device selected for illustration, the outer ends of the outer and inner elements 2 Land 3 are Welded or otherwise suitably joined together to provide a hot junction 4 which is adapted to be heated, as will presently appear. The opposite end of outer element 2 telescopes within and is brazed or otherwise joined to a conducting sleeve 5, the junction between the element 2 and sleeve 5 forming one co1 junction 6 for the thermocouple 1.

The opposite end of the sleeve 5 telescopes over and is joined at 7 to the adjacent end of a tubular lead conductor 8. The sleeve `5 may have a compression sleeve 9 xed thereon and a compression nut 10 is rotatable about sleeve 5 and cooperates with compression sleeve 9 for mounting the thermocouple 1, for example, in juxtaposition to a pilot burner as well understood in the art. An inner lead conductor 11, insulated at 12, extends through tubular conductor 8 and into sleeve 5, and, within sleeve 5, is brazed or otherwise joined to the adjacent end of inner thermocouple element 3 to form another cold junction 13 for the thermocouple 1. l

A second thermocouple, inserted as part of the inner conductor 11, consists of two thermocouple elements 14 and 15 of dissimilar metals, alloys, or other suitablev thermoelectric materials, for example, as set forth in connection with the thermocouple elements 2 and 3. The contiguous ends of elements 14 and 15 are joined'together to provide a thermojunction 16, and the elements 14 and 15 are arranged in series opposing relation to the elements 2 and 3 of the thermocouple 1 so that when the junction 16 is heated a millivoltage will be generated reverse to the millivoltage generatedby heating of the junction 4 of the thermocouple 1. Y

In the device as illustrated, the opposite end of element l5 is joined at 17 to the adjacent end of inner conductor 11. The opposite end of element 14 is joined at 18 to a lead conductor 19, which may be similar to conductor 11, and is insulated at 20. The conductor 19 extends through a tubular lead conductor 21, which may be similar to the tubular lead conductor 8, and has its inner end spaced axially from the end of the conductor 8. The gap between tubular conductors 21 and 8 is `bridged `by a conducting sleeve 22 which telescopes at its opposite ends over tubular conductors 21 and 8 and is joined, for example, by silver solder, or in any other suitable Inanner, to conductors 21 and 8, at- 23 and 24 respectively. The sleeve 22 has an opening 25 through which heat may be applied to the junction 16 as will presently apf pear. If desired, a ring 26 may be mounted for rotation on sleeve 22. This ring 26 is provided with an opening 27, as shown in Figures 1 and 2, for rotation into and out of register with the opening 25. When opening 27 is in register with opening 25, heat may be applied through the registering openings to the junction 16, and when opening 27 isout Yof register with opening senato the junction 16 is completely surrounded so that heat cannot be applied directly to the junction 16.

Fixed at 28 on the outer end of inner conductor I9 is a conducting connector stud or tip 29 which is adapted to seat against a terminal tip or connector member of a therrnoelectric control device to connect the thermoelectric generators, for example, in circuit with one end of the coil of an electromagnet for such device. The outer end of the tubular conductor 2l is belled out at 39, and an insulator 3l is interposed between the belled out end 30 of conductor 2l and the connector stud 29. A couple lead attaching nut 32 is rotatable about tubular conductor 21 and cooperates with the belled out end 3@ of con ductor 21 to attach the thermoelectric generator leads to the thermoelectric control device, with the tubular conductor 21, for example7 connected in circuit with the other end of the coil of the electromagnet lor such de vice.

The attaching nut 32 is adapted to be applied to a safety shut-off device, for example, in the manner shown in Harold A. Mantz Patent No. 2,409,947, patented October 22, l946, to connect the thermoelectric generators l and l4-l5 in circuit with the coil 34 of a safety control device which may, for example, be of the type shown in the Oscar J. Leins patent previously identified herein. With the device so applied, heating of the hot junction 4 of the thermocouple l, for example, by the flame of a pilot burner, will energize the magnet coil 34 sufficiently to hold a shut-off valve open, or a switch for such valve closed as long as the junction 4 is thus heated.

By rotating the ring 26 to register the opening 27 with the opening 25 and applying heat, as, for example, from a match or other small ame, to the junction le through the registering openings 27 and 25, there is generated at the thermocouple 14-15 a millivoltage which is reverse to the millivoltage generated by heating of the junction 4 of the thermocouple l, As a result, the coil 34 is deenergized sufficiently to release the armature and thereby the safety shut-off valve for movement to closed position shutting off the supply of fuel to the main burner.

The device thus provides a simple and convenient means for deenergizing the thermoelectric circuit without detaching the nut 32; also a device that may be handled, installed, and operated conveniently and effectively.

Figure 4 illustrates one embodiment of the present invention in which the therrnoelectric device is installed as a flash-back control.

In Figure 4 a fuel supply pipe or conduit 4t) leads to a burner 4l for the delivery of gaseous fuel thereto through a mixing chamber 43 to which air is admitted through adjustable air inlets (not shown), as well understood in the art.

Interposed in the fuel supply pipe 4D is a thermoelectric safety shut-off valve 42. The thermoelectric safety shut-off valve 42 may be, in general, of the type shown and described in Clarence Wantz Patent No. 2,307,870, issued January l2, 1943. Suice it to state that it comprises a valve body having an inlet at 44 for receiving gaseous or other fuel, and an outlet at 45 through which the fuel is delivered to the burner 4l. Contiguous sections of pipe are connected to inlet and outlet 45. A port or passage, shown more or less diagrammatically in dotted lines at 46, provides for communication between inlet 44 and outlet 45. A safety shut-off valve, shown in dotted lines at 47, is adapted to seat, for example, upon a valve seat at one end of port 46 to shut off the flow of fuel to the main burner 4l; also the flow of fuel for a pilot burner 4g located in juxtaposition or in lighting proximity to the burner 4l.

An electromagnet having a magnet frame 4@ and a coil 34', corresponding with the coil 34 previously described, is adapted for holding armature 5G connected to valve 47 in attracted position and thereby the valve 47 open when the hot junction 4 of thermoelectric generator l', which corresponds with the thermocouple l (lll previously described, is heated by the flame of the pilot burner 4S. When the pilot burner 48 is extinguished, the electromagnet, which is connected in circuit with the thermoelectric generator 1', ceases to hold the valve 47 open, and this valve moves to closed position, for example, unlcr the action of a spring 5l to shut o the supply of fuel to burner 4l; also the supply of fuel to the pilot burner 48.

A reset button 52 is adapted to be pressed inwardly to move valve 47 to open position with accompanying movement of armature 5l) to attracted position and to hold the armature in attracted position until the pilot burner 4S is ignited and heats the hot junction 4 of thermoelectric generator l sufficiently to retain armature attracted and valve 47 open. A ow interrupter valve 53 may be provided for shutting off the flow of fuel to the main burner 4i during the resetting operation and until valve 47 is held in open position by the electromagnet and button 5l is released and returns to its outwardly projecting position with accompanying operation of the flow interrupter valve 53 to open position. The details and mode of operation of a suitable reset and ow interrupter valve arrangement are shown and described in the above identified patent of Clarence Wantz; also in Charles V. Hildebrecht Patent No. 2,114,446, issued April 19, 1938.

The pipe S4 for supplying fuel to the pilot burner 48 may be connected, for example, as shown more or less diagrammatically at 55 to the interior of the body of the thermoelectric safety shut-off valve 42 between the above mentioned valve seats at opposite ends of the port or passage 46. In this way, valve 47, when in closed position, shuts off the supply of fuel to both the main burner 4l and pilot burner 48, and fuel flows to the pilot burner whenever the valve 47 is open and regardless of whether the flow interrupter valve 53 is open or closed.

lvl/ith the installation of the thermoelectric device in the embodiment of the present as a flash-back and safety control system as shown in Figure 4, the thermocouple ffl-15", with its hot junction 16 which corresponds with the thermocouple 14-15 and hot junction 16 previously described, are located in the mixing chamber 43 as shown in Figure 4, or in the intake manifold for the burner 4l. The attaching nut 32', which corresponds with the attaching nut 32 previously described, is applied to the safety shut-off valve 42 and connects the thermocouples l and l4-l5 in circuit with the coil 34 of the electromagnet.

in operation, cocking of the thermoelectric safety valve 42, by depressing the button 52, opens the valve 47, thus admitting gas which passes through the pipe 54 to the pilot burner 48. in cocking or resetting the thermoelectric safety sluit-olf valve, the flow interrupter valve membei' moves to closed position to shut off the flow of fuel to the main burner 4l during the resetting operation and until the pilot burner 43 is ignited and heats the hot junction of thernioelectrio generator I suiiiciently to hold valve 47 open. Then, upon release of button 52, valve member 53 moves to open position, admitting gas to the main burner 4i.

In case a flash-back condition occurs, the hot junction le' of the thermocouple l4-ll5 becomes heated. There is thereby generated at the thermocouple Mil-"5 a millivoltage which is reversed to the millivoltage generated by heating of the junction 4 of the thermocouple it. As a result, the coil 34 is deenergized suciently by the occurrence of a Hash-back condition to release the arma ture and thereby the valve 47 for movement to closed position shutting oliC the supply of fuel to the main burner 4i; also to the pilot burner 48.

While I have shown and described the present invention as a flash-back control system in which a llame is applied to the hot junction le of the thermoelectric device, it is to be understood that the invention is not limited to such uses, but may be used as a high temperature safety control apparatus by arranging the junction 16 or 16' of the therrnocouple 14-15, or 14-15, where it will be heated by the high temperature condition; also as a time control apparatus, and so that a plurality of thermoelectric generators will interact in timed relation to each other.

The embodiments of the invention shown in the drawings are for illustrative purposes only, and it is to be expressly understood that said drawings and the aocompanying specification are not to be construed as a denition of the limits or scope of the invention, reference being had to the appended claims for that purpose.

I claim:

l. In apparatus of the class described, in combination, a main burner, a pilot burner in juxtaposition to said main burner, a safety shut-off device for controlling fuel flow to both said burners having an electromagnet provided with a coil, and a thermoelectric generator and lead connection comp-rising an inner thermoelectric generator member, an inner lead conductor connected to said inner thermoelectric generator member to form an internal thermojunction, metallic tubular means enclosing said inner thermoelectric generator member and said internal thermojunction and comprising an outer tubular thermocouple generator member joined to said inner thermoelectric generator member to form a second thermojunction positioned to be heated by said pilot burner, and a pair of additional dissimilar thermoelectric generator members having a thermojunction therebetween and connected in circuit with said inner lead conductor land in opposing relation to said rst thermoelectric generator members and enclosed within said metallic tubular means, a ring having an opening therein rotatably disposed about said metallic tubular means to selectively cover and uncover the thermojunction between said additional thermoelectric generator members, the latter thermojunction being arranged to be heated by an abnormal condition when uncovered by said ring and to not be substantially heated by said condition when said ring is rotated to a covering relation thereto.

2. In apparatus of the class described, in combination, a main burner having a fuel intake, a pilot burner in juxtaposition to said main burner, a safety shut-off device for controlling the fuel ow to both said burners upon occurrence of an unsafe condition and having an electromagnet provided with a coil, and a thermoelectric generator and lead connection comprising an inner thermoelectric generator member, an inner lead conductor connected to said inner thermoelectric generator member to form an internal thermojunction, metallic tubular means enclosing said inner thermoelectric generator member and said internal thermojunction and comprising an outer tubular thermoelectric `generator member joined to said inner thennoelectrio generator member to form a second thermojunction positioned to be heated by said pilot burner, and a pair of additional dissimilar thermoelectric generator members having a thermojunction therebetween and connected in circuit with said inner lead conductor and in opposing relation to said rst thermoelectric generator members and enclosed within said metallic tubular means, a ring having an opening therein and being rotatable about said tubular means to selectively cover and uncover the thermojunction between said additional thermoelectrio generator members, the latter thermojunction being disposed -in the fuel intake for the main burner to be heated by the occurrence of a ash-back condition in said intake when uncovered by said ring, and to not be heated by said condition when said ring is rotated to a covering relation thereto, said latter thermojunction being thereby rendered non-responsive to said flash-back condition when uncovered.

References Cited in the le of this patent UNITED STATES PATENTS 2,137,199 Betz et al. Nov.. 15, 1938 2,285,866 Markle June 9, 1942 2,373,326 Miller Apr. 10, 1945 2,385,530 Paille Sept. 25, 1945 2,518,804 Marvin Aug. l5, 1950 2,691,056 Wollt Oct. 5, 1954 FOREIGN PATENTS 452,315 Great Britain Aug. 20, 1936 

